Duncan's Corner

One can create spiraling motions for particles using expressions. This method propagates a local up vector for the curl so that the twist direction does not go through pole flipping as the particle changes direction.

I just noticed that someone uploaded to YouTube an old animation I did for Siggraph way back in 1987. It is nice for me to see, as my own copy (on tape) had degraded to the point it was virtually unviewable.